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tolstoy:x:2076:10:Leo Tolstoy:/home/tolstoy:/bin/bash

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root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
jhancock:x:200:10:John Hancock:/home/jhancock:/bin/bash
ben:x:201:10:Ben Franklin:/home/ben:/bin/bash

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root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
jhancock:x:300:10:John Hancock:/home/jhancock:/bin/bash
ben:x:301:10:Ben Franklin:/home/ben:/bin/bash
abe:x:105:10:Honest Abe Lincoln:/home/abe:/bin/bash
tj:x:105:10:Thomas Jefferson:/home/tj:/bin/bash

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sort u1.passwd u2.passwd | tee merge1

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abe:x:105:10:Honest Abe Lincoln:/home/abe:/bin/bash
ben:x:201:10:Ben Franklin:/home/ben:/bin/bash
ben:x:301:10:Ben Franklin:/home/ben:/bin/bash
betsy:x:1110:10:Betsy Ross:/home/betsy:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
bin:x:1:1:bin:/bin:/sbin/nologin
dorothy:x:110:10:Dorothy Gale:/home/dorothy:/bin/bash
george:x:1100:10:George Washington:/home/george:/bin/bash
jhancock:x:200:10:John Hancock:/home/jhancock:/bin/bash
jhancock:x:300:10:John Hancock:/home/jhancock:/bin/bash
root:x:0:0:root:/root:/bin/bash
root:x:0:0:root:/root:/bin/bash
tj:x:105:10:Thomas Jefferson:/home/tj:/bin/bash
toto:x:110:10:Toto Gale:/home/toto:/bin/bash

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#! /bin/awk -f
BEGIN {FS = ":"}
{
    if ($1 in name) {
        if ($3 in uid)
            ; # 名称与uid完全一致，啥事不做
        else {
            print name[$1] > "dupusers"
            print $0 > "dupusers"
            delete name[$1]
            remove_uid_by_name($1)
        }
    } else if ($3 in uid) {
        print uid[$3] > "dupids"
        print $0 > "dupids"
        delete uid[$3]
        remove_name_by_uid($3)
    } else
        name[$1] = uid[$3] = $0
}
END {
    for (i in name)
        print name[i] > "unique1"
    close("unique1")
    close("dupusers")
    close("dupids")
}
function remove_uid_by_name(n, i, f)
{
    for (i in uid) {
        split(uid[i], f, ":")
        if (f[1] == n) {
            delete uid[i]
            break
        }
    }
}
function remove_name_by_uid(id, i, f)
{
    for (i in name) {
        split(name[i], f, ":")
        if (f[3] == id) {
            delete name[i]
            break
        }
    }
}

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awk -f splitout.awk merge1

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awk -F: '{ print $3 }' merge1 | sort -n -u > unique‑ids

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#! /bin/sh -
# newuids.sh [-c N] id‑file
count=1
while getopts "c:" opt
do
    case $opt in
    c) count=$OPTARG ;;
    esac
done
shift $(($OPTIND - 1))
IDFILE=$1
awk -v count=$count '
BEGIN {
    for (i = 1; getline id > 0; i++)
        uidlist[i] = id
    totalids = i
    for (i = 2; i <= totalids; i++) {
        if (uidlist[i-1] != uidlist[i]) {
            for (j = uidlist[i-1]+1; j < uidlist[i]; j++) {
                print j
                if (--count == 0)
                    exit
            }
        }
    }
}' $IDFILE

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newuids.sh -c 4 unique‑ids

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ben:x:201:10:Ben Franklin:/home/ben:/bin/bash     #组内第1行
ben:x:301:10:Ben Franklin:/home/ben:/bin/bash     #组内第2行
jhancock:x:200:10:John Hancock:/home/jhancock:/bin/bash  #下一组第1行
jhancock:x:300:10:John Hancock:/home/jhancock:/bin/bash  #下一组第2行

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rm -f old-new-list          # 先删除旧的映射文件，避免旧数据追加
old_ifs=$IFS                # 备份shell原始分隔符
IFS=:                       # 设置shell分隔符为冒号，read按冒号切割passwd字段

# 从dupusers文件读取，循环输出定向到 unique2
while read user passwd uid gid fullname homedir Shell
do
    # 重点：继续从同一个dupusers文件，再读下一行！
    if read user2 passwd2 uid2 gid2 fullname2 homedir2 Shell2
    then
        # 读到了第二行，判断两行用户名必须完全一样
        if [ $user = $user2 ]
        then
            # 输出：用户名 旧UID 新UID >>追加写入映射表 old‑new‑list
            printf "%s\t%s\t%s\n" $user $uid $uid2 >> old-new-list
            # 输出组装好的新passwd记录，输出重定向到 unique2
            echo "$user:$passwd:$uid2:$gid:$fullname:$homedir:$Shell"
        else
            # 两行用户名不一样，文件错乱，报错到标准错误，退出脚本
            echo $0: out of sync: $user and $user2 >&2
            exit 1
        fi
    else
        # 想读第二行，但是读到文件末尾读不到数据了，说明dupusers文件格式损坏（只有孤零零一行，没有配对）
        echo $0: no duplicate for $user >&2
        exit 1
    fi
done < dupusers > unique2

IFS=$old_ifs    # 恢复原来的IFS，还原shell环境

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ben:x:301:10:Ben Franklin:/home/ben:/bin/bash
jhancock:x:300:10:John Hancock:/home/jhancock:/bin/bash

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count=$(wc -l < dupids)

# set -- arg1 arg2 arg3 …
# 直接改写 shell 的位置参数 $1 $2 $3 $4 …，把原来的位置参数全部替换成后面给出的值。
# set -- 4 5 6 7
# $(...) 命令替换，老式使用反引号 `cmd`，现代推荐写法：$(命令)，执行括号内部的 shell 命令，捕获这个命令打印到标准输出的全部内容且换行被shell换成空格，得到字符串："4 5 6 7"，把输出结果替换到脚本当前位置。
set -- $(newuids.sh -c $count unique-ids)
IFS=:
while read user passwd uid gid fullname homedir Shell
do
    newuid=$1
    shift
    echo "$user:$passwd:$newuid:$gid:$fullname:$homedir:$Shell"
    printf "%s\t%s\t%s\n" $user $uid $newuid >> old-new-list
done < dupids > unique3
IFS=$old_ifs

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abe:x:4:10:Honest Abe Lincoln:/home/abe:/bin/bash
tj:x:5:10:Thomas Jefferson:/home/tj:/bin/bash
dorothy:x:6:10:Dorothy Gale:/home/dorothy:/bin/bash
toto:x:7:10:Toto Gale:/home/toto:/bin/bash

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sort -k 3 -t : -n unique[123] > final.password

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find / -user $user -print | xargs chown $newuid

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find / -user $user -print0 | xargs -0 chown $newuid

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while read user old new
do
    echo "find / -user $user -print | xargs chown $new"
done < old-new-list > chown-files
chmod +x chown-files

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find / -nouser -o -nogroup -ls